Castable explosive compositions containing technical grade 2,4,6-trinitrotoluene (TNT), when cast in artillery shells, etc., often exhibit undesirable properties, such as exudation of oily impurities on storage, cavitation, brittleness, cracking, poor adhesion to the case, etc., which adversely affect ballistic performance and sensitivity of the cast to impact. In the past various methods have been proposed for overcoming such disadvantageous properties, but these have been only partially successful. For example, U.S. Pat. No. 3447980 discloses that solid cast TNT explosives which are essentially free from exuding oils and voids, are less brittle and possesses superior compressive strength and adhesion to the case, can be obtained by incorporating into the molten TNT compositions a polyurethane elastomeric system consisting of the reaction product of a prepolymer from 2,4-tolylene diisocyanate and 1,4-polybutylene glycol with hydrogenated castor oil. However, the liquid castable compositions are deficient in that they have limited pot life (i.e. require limited melt time and pour time before gellation and irreversible chemical curing of the polyurethane elastomer takes place in the TNT); and the cast compositions obtained therefrom on solidification are also deficient in that they are not uniformly remeltable, that is, on heating above the melting point of TNT, the composition separates into a liquid TNT phase and a solid elastomer phase, which prevents reprocessing to produce a solidified cast of uniform composition and constant explosive characteristics. U.S. Pat. No. 3706609 discloses that cast TNT explosives, which are free from voids and exuding oils and are capable of being remelted and recast while retaining good homogeneity, can be obtained by incorporating into the molten compositions a small amount of nitrocellulose or other thermoplastic cellulosic resin. However, such cast compositions are relatively brittle and possess inferior mechanical strength and adhesion to the artillery case as compared with the compositions containing the aforementioned polyurethane elastomer.